Electronic control unit

ABSTRACT

An electronic control device having a high heat dissipating ability includes a printed board secured to an enclosure and interposed between a case and a cover with screws passing through the printed board. Thermally conductive thin film layers made of copper foil are formed in parallel on a mount face and an opposite mount face of the printed board and inside the printed board so as to be thermally separated from each other. A protrusion is provided on the cover and protrudes beyond a bottom part of the cover toward the position where an electronic component is mounted. A flexible, semi-solid thermally conductive material is placed between an end face of the protrusion and the opposite mount face of the printed board corresponding to the position where the electronic component is mounted to be in contact with the end face and the opposite mount face.

CROSS REFERENCE TO RELATED APPLICATION

This is a continuation of U.S. patent application Ser. No. 10/393,258,which was filed on 21 Mar. 2003 Now U.S. Pat. No. 6,816,377 the contentsof which are incorporated herein by reference. This application is basedupon, and claims the benefit of priority of, and incorporates byreference the contents of prior Japanese Patent Application No.2002-92495 filed Mar. 28, 2002.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to an electronic control unit which isplaced in, for example, an engine compartment of a vehicle.

2. Description of the Related Art

In an electronic control unit (ECU), for example, used for control of avehicle, a microcomputer for performing operational processing, aninput/output circuit connected to an external load, a sensor, a powersupply circuit for supplying power to circuits, and like components havebeen conventionally placed on a substrate. Then, these circuits andsubstrate are housed within an enclosure typically consisting of a caseand a cover.

The electronic components constituting the above-mentioned circuitsgenerate heat during their operation. An excessively increasedtemperature of the electronic components adversely affects the operationof the components. Therefore, in order to reduce a temperature of theelectronic components, a method for transferring the heat to thesubstrate, and the like, so as to diffuse the heat is known.

Moreover, as shown in FIG. 12, for an electronic component (for example,a semiconductor chip of a power transistor) P1 that generates aparticularly large amount of heat, a method using a radiator fin P2 orthe like has been used to efficiently dissipate the heat generated fromthe electronic component P1 toward a case P3. However, given currentproduct demands, the electronic control unit has been required to havehigher function and performance levels, while the heat generated fromthe electronic component P1 increases.

Accordingly, in order to dissipate a larger amount of heat from theheat-generating electronic component P1, the structure as shown in FIG.13 has been adopted. In this structure, a large piece of copper foil P6is placed on the region where the electronic component P1 (morespecifically, a heat sink P5) is attached on a substrate P4. The heat isdissipated via holes P7 to other larger pieces of copper foil P8 and thelike. In this method, however, since an effective wiring area on thesubstrate P4 is decreased, the substrate P4 in a large size isaccordingly required, leading to an increase in cost.

On the other hand, miniaturization of the electronic control unit isalso desirable. In order to respond to such a need for miniaturization,that is, a method for miniaturizing the components in accordance withthe development of semiconductor integration techniques, a method formaking a number of circuits IC-compatible and the like have been used.However, the use of such methods causes an increase in temperature ofthe electronic component P1.

As measures against the increase in temperature of the electroniccomponent P1, it has been proposed to use the expensive electroniccomponent P1 which results in little power loss. Additionally, it hasbeen proposed to mount the components on the radiator fin P2 or toincrease the size of the substrate P4 to a certain degree so as toimprove heat dissipation. However, these methods result in increasedcosts.

It is also conceivable to make the heat-generating electronic componentP1 itself highly heat resistant. However, such a measure is notnecessarily preferable because peripheral components placed at a highdensity also have an increased temperature due to heat transferred fromthe substrate P4, whereby the size of the substrate P4 must be increasedto a certain degree or the peripheral components must be highheat-resistant components.

SUMMARY OF THE INVENTION

The present invention has been developed to solve the above problems,and has an object of providing an electronic control unit having a highheat dissipating ability, which can be easily fabricated at a low cost.

(1) A first aspect of the present invention relates to an electroniccontrol unit. The unit includes a substrate having a mount face (i.e.first) and an opposite mount face (i.e. second), an electronic componentthat generates heat and is placed on a side of the mount face, and anenclosure consisting of a plurality of enclosure members to house thesubstrate. A portion of the enclosure members on a side of the oppositemount face is made to protrude toward a position where the electroniccomponent is mounted, while a flexible, thermally conductive material isplaced between the protrusion and the opposite mount face so as to be incontact with a side of the protrusion and the side of the opposite mountface. The enclosure member having the protrusion and the substrate arebrought to be in direct contact with each other or in contact with eachother through a spacer having a predetermined thickness so as to fix theassembly.

Since the flexible, thermally conductive material is provided betweenthe protrusion of the enclosure member and the substrate in anembodiment of the present invention, it ensures close adherence betweenthe enclosure member and the substrate on their large faces through thethermally conductive material. As a result, the heat dissipationproperties are enhanced.

Moreover, since the enclosure member having the protrusion and thesubstrate are brought into direct contact with each other or through aspacer, the dimensional accuracy of a gap between the substrate and theprotrusion can be ensured. As a result, since the thermally conductivemember placed in the gap can be very small, such a structure contributesto a reduction in cost.

Moreover, even in the case where a thermally conductive material havingan inferior thermal conductivity to those of the enclosure or athermally conductive thin film layer (for example, a copper foil) on thesurface of the substrate, the maximum heat dissipation properties can beensured because the gap can be normally reduced as described above.

(2) According to a second aspect of the present invention, a thermallyconductive thin film layer (for example, a piece of copper foil which isa thin, metallic film) having a higher thermal conductivity than that ofa periphery thereof, is provided on the mount face so as to overlap aregion obtained by projecting the electronic component thereon.

More specifically, the thermally conductive thin film layer is providedso as to (partially or entirely) overlap the region obtained byprojecting the electronic component onto the substrate side, whereby theheat transfer properties from the electronic component side toward thesubstrate side can be enhanced. Although it is preferred that thesentence “the thermally conductive thin film layer is provided so as to(partially or entirely) overlap the region obtained by projecting” means“the thermally conductive thin film layer is provided on a half or moreof the region obtained by projecting” in terms of heat transferproperties, it is more preferred that this sentence mean “the thermallyconductive thin film layer is provided so as to completely include theregion obtained by projecting.” The same is applied to the following.

(3) According to a third aspect of the present invention, a thermallyconductive thin film layer having a higher thermal conductivity thanthat of a periphery thereof is provided on the opposite mount face so asto overlap a region obtained by projecting an end face of theprotrusion.

More specifically, the thermally conductive thin film layer is providedso as to (partially or entirely) overlap the region obtained byprojecting the protrusion thereon, thereby enhancing the heat transferproperties from the substrate side toward the enclosure side.

(4) According to a fourth aspect of the present invention, thermallyconductive thin film layers, each having a higher thermal conductivitythan that of a periphery thereof, are provided respectively on the mountface and the opposite mount face so as to overlap a region obtained byprojecting the electronic component thereon, and the thermallyconductive thin film layers are connected to each other through a hole.Since the thermally conductive thin film layers provided on the mountface and the opposite mount face of the substrate are connected to eachother through a hole In an embodiment of the present invention, the heattransfer properties between both surfaces of the substrate can beenhanced.

(5) According to a fifth aspect of the present invention, thermallyconductive thin film layers, each having a higher thermal conductivitythan that of a periphery thereof, are provided respectively on the mountface, the opposite mount face, and inside the substrate so as to overlapa region obtained by projecting the electronic component thereon.

Since the thermally conductive thin film layers are provided on themount face and the opposite mount face of the substrate, and inside thesubstrate In an embodiment of the present invention, the heat transferproperties between both surfaces of the substrate can be enhanced.

(6) According to a sixth aspect of the present invention, an area of thethermally conductive thin film layer on the side of the opposite mountface is formed larger than that on the side of the mount face.

The present invention has advantages in that thermal conductivity can befurther improved in a direction from the mount face of the substrate toits opposite mount face and in that the heat diffused to the peripherycan be absorbed.

(7) According to a seventh aspect of the present invention, other thanthe thermally conductive thin film layer corresponding to the regionobtained by projecting the electronic component, a thermally conductivethin film layer is provided at another location of the substrate, andthe thermally conductive thin film layers are thermally separated fromeach other.

Since the thermally conductive thin film layers are thermally separatedfrom each other In an embodiment of the present invention, the adverseheat diffusion to the peripheral components can be restrained.

(8) An eighth aspect of the present invention relates to an electroniccontrol unit including a substrate having a mount face and an oppositemount face, an electronic component generating heat that is placed on aside of the mount face, and an enclosure housing the substrate. A partof the enclosure on the side of the mount face is made to protrudetoward the electronic component, while a flexible, thermally conductivematerial is placed between the protrusion and the electronic componentso as to be in contact with a side of the protrusion and a side of theelectronic component.

In an embodiment of the present invention, the thermally conductivematerial is placed not on the side of the opposite mount face of thesubstrate, but on the mount face.

As a result, since the heat can be transferred from the electroniccomponent toward the enclosure side through the thermally conductivematerial without passing through the substrate, good heat dissipationproperties can be obtained so as to restrain the effects of heat on theother electronic components on the substrate. Moreover, the mountingarea for wiring and the electronic components on the substrate can alsobe increased.

(9) According to a ninth aspect of the present invention, the electroniccomponent is in contact with the thermally conductive material through aradiator member that is integrally molded with the electronic component.As a result, heat dissipation can be efficiently performed.

(10) A tenth aspect of the present invention relates to an electroniccontrol unit including a substrate that has a mount face and an oppositemount face, an electronic component that generates heat and that isplaced on a side of the mount face, and an enclosure that houses thesubstrate. A part of the enclosure on a side of the opposite mount faceis made to protrude toward a position where the electronic component ismounted, while a flexible, thermally conductive material is placedbetween the protrusion and the opposite mount face, and at least onesurface of the protrusion and the opposite mount face. At least onesurface is in contact with the thermally conductive material and isformed to have a concave-convex shape.

More specifically, in an embodiment of the present invention, theflexible, thermally conductive material is placed between the protrusionof the enclosure and the opposite mount face of the substrate, while atleast one of a surface of the protrusion and the opposite mount face isformed to have a convex-concave shape.

As a result, the contact area with the thermally conductive material isincreased to improve the heat dissipation properties. Therefore, even inthe case where an electronic component that generates a large amount ofheat is to be mounted, another special structure (for example, anincrease in size of the protrusion or the thermally conductive thin filmlayer) is not needed, thereby contributing to a reduction of theenclosure in terms of size or a reduction in cost.

(11) According to an eleventh aspect of the present invention, athermally conductive thin film layer having a higher thermalconductivity than that of a periphery thereof is provided on theopposite mount face, while the convex portion of the convex-concaveshape is provided on the thermally conductive thin film layer withsolder. Since the convex portion is made of a solder in an embodiment ofthe present invention, the convex-concave shape can be easily formed ata low cost.

(12) According to a twelfth aspect of the present invention, theprotrusion having the concave-convex shape is integrally formed with theenclosure. Since the protrusion and the concave-convex shape can beintegrally formed by, for example, casting or injection molding, theconcave-convex shape can be accurately formed even at a low cost.Moreover, since the dimensional accuracy of the gap between theprotrusion and the substrate is enhanced, the minimal, yet thermallyconductive material is sufficient for use. At the same time, the heattransfer performance can be maintained at a high level.

(13) According to a thirteenth aspect of the present invention, theconvex portion and the concave portion on the opposite mount face arerespectively formed so as to correspond to the convex portion and theconcave portion on an end face of the protrusion. Since the gap betweenthe protrusion and the substrate can be made uniform in an embodiment ofthe present invention, the heat transfer performance can be maximized.Moreover, the stress due to thermal expansion can also be made uniform.Furthermore, the minimal thermally conductive material is sufficient foruse, while the heat transfer performance can be maintained at a highlevel.

(14) According to a fourteenth aspect of the present invention,thermally conductive thin film layers, each having a higher thermalconductivity than that of a periphery thereof, are provided on the mountface and the opposite mount face so as to overlap a region obtained byprojecting the electronic component thereon, and the thermallyconductive thin film layers are connected to each other via a hole. Thisstructure allows the heat transfer properties to be enhanced asdescribed above.

(15) According to a fifteenth aspect of the present invention, thermallyconductive thin film layers, each having a higher thermal conductivitythan that of a periphery thereof, are provided on the mount face and theopposite mount face and inside the substrate so as to overlap a regionobtained by projecting the electronic component thereon. This structureallows the heat transfer properties to be enhanced as described above.

(16) According to a sixteenth aspect of the present invention, otherthan the thermally conductive thin film layer corresponding to theregion obtained by projecting the electronic component, a thermallyconductive thin film layer is provided at another location of thesubstrate, and the thermally conductive thin film layers are thermallyseparated from each other. This structure prevents the heat from beingtransferred to the peripheral electronic components and the like, asdescribed above.

(17) A seventeenth aspect of the present invention relates to anelectronic control unit including a substrate having a mount face and anopposite mount face, an electronic component that generates heat andthat is placed on a side of the mount face and an enclosure housing thesubstrate. A solid thermally conductive member is placed between theopposite mount face and the enclosure so as to be in contact with a sideof the opposite mount face and a side of the enclosure, while aflexible, thermally conductive material is placed between the thermallyconductive member and the enclosure so as to be in contact with a sideof the thermally conductive member and the side of the enclosure. Sincethe enclosure, the thermally conductive material, the thermallyconductive member, and the substrate are placed in this order, high heatdissipation properties can be ensured.

Moreover, since it is not necessary to provide a protrusion on theenclosure side in advance, the common enclosure can be utilized.Furthermore, even if there is a change in layout of the electroniccomponents and the like, it is not necessary to redesign the enclosure.Thus, such a structure is advantageous with its high general-purposeproperties.

(18) According to an eighteenth aspect of the present invention, thethermally conductive member is soldered to the opposite mount face. As aresult, heat transfer performance can be ensured. Moreover, in the casewhere, for example, a ceramic chip and the like is used as the thermallyconductive member, the thermally conductive member can be attached tothe substrate by a so-called surface mounting technique in the samemanner as for the electronic components.

(19) According to a nineteenth aspect of the present invention, at leastone surface of the thermally conductive member and the enclosure, the atleast one surface being in contact with the thermally conductivematerial, is formed to have a convex-concave shape. The concave-convexshape increases the contact area with the thermally conductive materialas described above, thereby improving the heat dissipation properties.

(20) According to a twentieth aspect of the present invention, theconvex-concave shape of the enclosure is integrally formed with theenclosure. As described above, the integral formation allows theconcave-convex shape to be accurately fabricated at low cost. Moreover,since dimensional accuracy of the gap between the thermally conductivemember and the enclosure is increased, the area used by the thermallyconductive member is minimized, while the heat transfer performance maybe maintained at a high level.

(21) According to a twenty-first aspect of the present invention, theconvex-concave shape of the thermally conductive member is integrallyformed with the thermally conductive member. The present invention hasthe same effect as that of the above-described twentieth aspect.

(22) According to a twenty-second aspect of the present invention, theconvex portion and the concave portion of the enclosure are respectivelyformed so as to correspond to the convex portion and the concave portionof the thermally conductive member.

Since a gap between the thermally conductive member and the enclosurecan be made uniform in an embodiment of the present invention, the heattransfer performance can be maximized. Moreover, stress due to thermalexpansion can be made uniform.

Furthermore, the minimal amount of thermally conductive material issufficient for use, while the heat transfer performance can bemaintained at a high level.

(23) A twenty-third aspect of the present invention relates to anelectronic control unit including a substrate having a mount face and anopposite mount face, an electronic component that generates heat that isplaced on a side of the mount face, and an enclosure that houses thesubstrate. A flexible, thermally conductive material is placed between apart of the enclosure on the side of the mount face and the electroniccomponent so as to be in contact with a side of the enclosure and a sideof the electronic component, while a surface of the side of theenclosure in contact with the thermally conductive material is formed tohave a convex-concave shape.

Since the heat is transferred from the electronic component side towardthe enclosure side through the thermally conductive material withoutpassing through the substrate in an embodiment of the present invention,high heat dissipation properties can be obtained. Moreover, the effectof heat on the peripheral electronic components on the substrate can beprevented. Furthermore, since the convex-concave shape is formed on theenclosure side, the contact area is large, which in turn providesexcellent heat dissipation properties.

(24) According to a twenty-fourth aspect of the present invention, theconvex-concave shape is integrally formed with the enclosure. Asdescribed above, the integral formation allows the concave-convex shapeto be accurately fabricated at a low cost. Moreover, since dimensionalaccuracy of the gap between the thermally conductive material and theenclosure is increased, the thermally conductive material that is usedis minimized, while the heat transfer performance is maintained at ahigh level.

(25) According to a twenty-fifth aspect of the present invention, theelectronic component is in contact with the thermally conducive materialthrough a radiator member (for example, a heat sink) that is integrallymolded with the electronic component. Since the electronic componentradiates heat through the radiator member In an embodiment of thepresent invention, high heat dissipation properties can be obtained.

(26) A twenty-sixth aspect of the present invention relates to anelectronic control unit including a substrate having a mount face and anopposite mount face, an electronic component that generates heat andthat is placed on a side of the mount face, and an enclosure that housesthe substrate. A part of the enclosure on a side of the opposite mountface is made to protrude toward a position where the electroniccomponent is mounted, while a flexible, thermally conductive material isplaced between the protrusion and the opposite mount face so as to be incontact with a side of the protrusion and the side of the opposite mountface. A movement-stopping part protruding toward a side of the thermallyconductive material, for preventing the thermally conductive materialfrom moving, is provided on at least one surface of the protrusion, andthe opposite mount face, the at least one surface being in contact withthe thermally conductive material.

Since the movement-stopping part for preventing the thermally conducivematerial from moving, which is placed on the surface side of theprotrusion, is provided In an embodiment of the present invention, thethermally conductive material does not fall out from a space between theprotrusion and the substrate. For example, in the case where thethermally conductive material has a low flexibility, for example, in asheet-like shape, it is suitable to provide convex portions at aplurality of locations in the periphery of the thermally conducivematerial and at the thermally conductive material itself. On the otherhand, in the case where the thermally conductive material has a highflexibility, it is suitable to provide a frame-like convex portion whichcontinuously surrounds the periphery of the thermally conductivematerial.

(27) According to a twenty-seventh aspect of the present invention, athermally conductive thin film layer having a higher thermalconductivity than that of a periphery thereof is provided on theopposite mount face of the substrate corresponding to the position wherethe electronic component is mounted, while the movement-stopping part isprovided on a surface of the thermally conductive thin film layer with asolder. In an embodiment of the present invention, for example, aframe-like movement-stopping part can be easily provided at a low cost,without requiring any processing or other components.

(28) According to a twenty-eighth aspect of the present invention, themovement-stopping part is integrally formed with the protrusion. Theintegral formation facilitates the formation of the movement-stoppingpart and improves the dimensional accuracy.

(29) A twenty-ninth aspect of the present invention relates to anelectronic control unit including a substrate having a mount face and anopposite mount face, an electronic component that generates heat and isplaced on a side of the mount face, and an enclosure that houses thesubstrate. A solid, thermally conductive member is placed between theopposite mount face and the enclosure so as to be in contact with a sideof the opposite mount face and a side of the enclosure, while aflexible, thermally conductive material is placed between the thermallyconductive member and the enclosure so as to be in contact with a sideof the thermally conductive member and the side of the enclosure. Amovement-stopping part protruding toward a side of the thermallyconductive material, for preventing the thermally conductive materialfrom moving, is provided on at least one surface of the opposite mountface and the thermally conductive member. The at least one surface beingin contact with the thermally conductive material.

In an embodiment of the present invention, the thermally conductivemember is placed between the opposite mount face and the enclosure,while the thermally conductive material is placed between the thermallyconductive member and the enclosure. Moreover, the movement-stoppingpart is provided on the surface facing the thermally conductive materialin contact therewith.

As a result, high heat dissipation properties can be ensured. In thecase where the movement-stopping part is provided on the thermallyconductive member side, in particular, standardization of the enclosurecan be ensured. At the same time, the degree of freedom in substratedesigning is improved, thereby largely contributing to a reduction incost.

(30) According to a thirtieth aspect of the present invention, themovement-stopping part is integrally formed with the thermallyconductive member or the enclosure. The integral formation facilitatesthe formation of the movement-stopping part and improves the dimensionalaccuracy.

(31) According to a thirty-first aspect of the present invention, thethermally conductive member is soldered onto the opposite mount face.

As a result, the heat transfer performance can be sufficiently ensured.In the case where, for example, a ceramic chip and the like is used asthe thermally conductive member, the thermally conductive member can beattached to the substrate by a so-called surface mounting technique inthe same manner as the electronic components.

(32) According to a thirty-second aspect of the present invention,thermally conductive thin film layers, each having a higher thermalconductivity than that of a periphery thereof, are respectively providedon the mount face and the opposite face so as to overlap a regionobtained by projecting the electronic component thereon, while thethermally conductive thin film layers are connected to each otherthrough a hole.

As a result, the heat transfer properties related to a thicknessdirection of the substrate can be enhanced, as described above.

(33) According to a thirty-third aspect of the present invention,thermally conductive thin film layers, each having a higher thermalconductivity than that of a periphery thereof, are respectively providedon the mount face, the opposite face, and inside the substrate so as tooverlap a region obtained by projecting the electronic componentthereon.

As a result, the heat transfer properties related to a thicknessdirection of the substrate can be enhanced, as described above.

(34) According to a thirty-fourth aspect of the present invention, otherthan the thermally conductive thin film layer corresponding to theregion obtained by projecting the electronic component thereon, athermally conductive thin film layer is provided at another location ofthe substrate, while the thermally conductive thin film layers arethermally separated from each other.

Since the thermally conductive thin film layers are thermally separatedfrom each other, the effect of heat on the electronic components and thelike at the periphery of the substrate can be restrained.

(35) A thirty-fifth aspect of the present invention relates to anelectronic control unit including a substrate having a mount face and anopposite mount face, an electronic component that generates heat andthat is placed on a side of the mount face, and an enclosure housing thesubstrate. A flexible, thermally conductive material is placed between apart of the enclosure on the side of the mount face and the electroniccomponent so as to be in contact with a side of the enclosure and a sideof the electronic component. A movement-stopping part protruding towarda side of the thermally conductive material, for preventing thethermally conductive material from moving, is provided on at least onesurface of the electronic component and the enclosure, the at least onesurface being in contact with the thermally conductive material.

Since the heat is transferred from the electronic component toward theenclosure side through the thermally conductive material and not throughthe substrate, little heat is transferred to the substrate side, therebyproviding high heat dissipation properties. Moreover, thermal effects onthe other components mounted on the substrate can be reduced.Furthermore, the movement-stopping part can prevent the thermallyconductive material from flowing out.

(36) According to a thirty-sixth aspect of the present invention, themovement-stopping part is integrally formed with the enclosure. Sincethe movement-stopping part is integrally formed with the enclosure, itsformation is simple. At the same time, high dimensional accuracy isobtained.

(37) According to a thirty-seventh aspect of the present invention, theelectronic component is in contact with the thermally conductivematerial through a radiator member (for example, a heat sink) integrallymolded with the electronic component. As a result, since the electroniccomponents can radiate heat through the radiator member, the presentinvention is effective because of its high heat dissipation properties.

(38) According to a thirty-eighth aspect of the present invention, themovement-stopping part is a frame part surrounding a periphery of thethermally conductive material, formed in a convex shape. Since thepresent invention prevents the thermally conductive material fromflowing out or falling out, the thermally conductive material can beprevented from flowing out even if, for example, the electronic controlunit is placed in a longitudinal direction.

Moreover, since the periphery of the position where the thermallyconductive material is placed is surrounded by the frame part, it is notnecessary to thinly apply the thermally conductive material thereto. Thethermally conductive material has an even thickness by merely placingthe thermally conductive material within the frame with a simple process(for example, potting the thermally conductive material in a mountainousshape).

A metal material having a higher thermal conductivity than, for example,that of a resin such as an epoxy resin serving as a substrate materialand the like can be used as the solid thermally conductive memberdescribed above. In view of the thermal conductivity, a general alloy ormetal material having a thermal conductivity of 20 to 400 W/m·K can beused.

The thermally conductive material is, for example, a flexible semi-solid(or a gel) whose shape is easily deformed upon pressing. A silicon-typematerial having a higher thermal conductivity than, for example, that ofa resin such as an epoxy resin serving as a substrate material is usedas the thermally conductive material. In view of the thermalconductivity, a material having a thermal conductivity of about 1 to 3W/m·K can be used.

A thin film layer made of, for example, a copper foil having a higherthermal conductivity than that of a resin such as an epoxy resin thatserves as a substrate material can be used as the thermally conductivethin film layer described above. In view of the thermal conductivity,copper having a thermal conductivity of about 398 W/m·K can be used.

A solid metal material, for example, having a higher thermalconductivity than that of a resin that serves as a molding material canbe used as the radiator member (for example, a heat sink). In view ofthe thermal conductivity, a general alloy or metal material having athermal conductivity of 20 to 400 W/m·K can be used.

Further areas of applicability of the present invention will becomeapparent from the detailed description provided hereinafter. It shouldbe understood that the detailed description and specific examples, whileindicating the preferred embodiment of the invention, are intended forpurposes of illustration only and are not intended to limit the scope ofthe invention.

BRIEF DESCRIPTION OF THE DRAWINGS

The present invention will become more fully understood from thedetailed description and the accompanying drawings, wherein:

FIG. 1 is a cross-sectional view showing an electronic control unit ofEmbodiment 1;

FIG. 2 is a cross-sectional view showing an electronic control unit ofEmbodiment 2;

FIG. 3 is a cross-sectional view showing an electronic control unit ofEmbodiment 3;

FIGS. 4A and 4B are plan views, each showing a movement-stopping part ofthe electronic control unit of Embodiment 3;

FIG. 5 is a cross-sectional view showing an electronic control unit ofEmbodiment 4;

FIG. 6 is a cross-sectional view showing an electronic control unit ofEmbodiment 5;

FIG. 7 is a cross-sectional view showing an electronic control unit ofEmbodiment 6;

FIG. 8 is a cross-sectional view showing an electronic control unit ofEmbodiment 7;

FIG. 9 is a cross-sectional view showing an electronic control unit ofEmbodiment 8;

FIG. 10 is a cross-sectional view showing an electronic control unit ofEmbodiment 9;

FIG. 11 is a cross-sectional view showing an electronic control unit ofEmbodiment 10;

FIG. 12 is a cross-sectional view showing an electronic control unit ofthe prior art; and

FIG. 13 is a cross-sectional view showing an electronic control unit ofthe prior art.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Hereinafter, exemplary embodiments of an electronic control unit of thepresent invention will be described. The following description of theexemplary embodiments is merely exemplary in nature and is in no wayintended to limit the invention, its application, or uses.

(Embodiment 1)

a) First, an electronic control unit of Embodiment 1 will be describedwith reference to FIG. 1. As shown in FIG. 1, an electronic control unit(ECU) 1 in Embodiment 1 includes a printed board 5 on which aheat-generating electronic component (for example, a semiconductor chip)3 is mounted, and an enclosure 7 that houses the printed board 5therein.

The enclosure 7 is made of, for example, a metal such as aluminum or thelike. The enclosure 7 is constructed, for example, by an approximatelyrectangular box-shaped case 9 and an approximately rectangularplate-like cover 13. The case 9 has an open end on one side (the lowerside in FIG. 1). The cover 13 for closing the open side (opening 11) ofthe case 9 has a recession with a small depth. The case 9 and the cover13 are connected to each other at their four corners through screws 15.

In connection between the case 9 and the cover 13, the printed board 5is secured to the enclosure 7 by the screws 15 that pass through theprinted board 5 while being interposed between the case 9 and the cover13. Therefore, an opposite mount face 5 b of the printed board 5 on thecover 13 side (a face opposed to a mount face 5 a on which theelectronic component 3 is mounted) and a connection face 13 a providedat the outer periphery of the cover 13 are positioned on the same plane.

The printed board 5 is made of, for example, a resin material such asepoxy resin. A plurality of thermally conductive thin film layers 17 a,17 b and 17 c (collectively designated by the reference numeral 17) areformed in parallel on the mount face 5 a and the opposite mount face 5 band inside the printed board 5, respectively. Each of the thermallyconductive thin film layers 17 a to 17 c is made of a copper foil.

More specifically, on the mount face 5 a and the opposite mount face 5 band inside the printed board 5, the thermally conductive thin filmlayers 17 a, 17 b, and 17 c formed on the respective planes areseparated from each other in a vertical direction in FIG. 1 as well asin a horizontal direction thereof. Therefore, the thermally conductivethin film layers 17 a, 17 b, and 17 c are also thermally separated fromeach other.

The electronic component 3 is molded along with a lead frame 19 and abonding wire 21 through a resin 23. The molded electronic component 3(hereinafter, also referred to as a molded component 25) has a main bodypart 25 a which is adhered to the thermally conductive thin film layer17 a formed on the mount face 5 a of the printed board 5 through anadhesive. The lead frame 19 is soldered onto another thermallyconductive thin film layer 17 a on the mount face 5 a.

The thermally conductive thin film layers 17 are formed so as to overlapa region obtained by projecting the electronic component 3 onto theprinted board 5 side (that is, so as to be larger than a projectedregion). Among them, the thermally conductive thin film layer 17 a hasthe same shape as the lower end face of the main body part 25 a of themolded component 25, whereas the thermally conductive thin film layers17 b and 17 c have substantially the same shape as that obtained byprojecting the electronic component 3 onto the printed board 5.

The cover 13 has a protrusion 27 in an approximately trapezoidal shape.The protrusion 27 projects beyond a bottom portion 13 b of the cover 13toward the position where the electronic component 3 is mounted. An endface 27 a of the protrusion 27 is formed flat so as to be parallel tothe opposite mount face 5 b of the printed board 5. Since the cover 13is formed, for example, by pressing, a bottom side of the protrusion 27is concave so as to correspond to the shape of the protrusion 27.

In this Embodiment 1, in particular, a flexible semi-solid thermallyconductive material 29 is placed between the end face 27 a of theprotrusion 27 and the opposite mount face 5 b of the printed board 5corresponding to the position where the electronic component 3 ismounted (that is, a region obtained by projecting the electroniccomponent 3 thereon) so as to be in contact with the end face 27 a andthe opposite mount face 5 b. The thermally conductive material 29 ismade of, for example, a silicon type gel resin material containing ametal filler.

The thermally conductive thin film layer 17 b having a similar shape tothat of the region obtained by projecting the electronic component 3thereon is formed on a part of the surface of the opposite mount face 5b of the printed board 5, the part being in contact with the thermallyconductive material 29. The thermally conductive thin film layer 17 c,which is formed inside the printed board 5 so as to correspond to theposition of the thermally conductive thin film layer 17 b, is alsoformed to have a similar shape to the projected shape of the electroniccomponent 3.

b) In this Embodiment 1, the thermally conductive thin film layers 17are successively placed in a vertical direction in FIG. 1 so as tocorrespond to the position where the electronic component 3 is mounted.At the same time, the thermally conductive material 29 is placed betweenthe printed board 5 and the protrusion 27 of the cover 13 so as to bepressed therebetween to be in contact therewith. Therefore, the heatgenerated by the electronic component 3 can be efficiently dissipated tothe outside through the cover 13 at a lower cost than in a conventionalstructure.

Moreover, in this Embodiment 1, since the printed board 5 is pressed bythe cover 13 in direct contact therewith so as to be secured thereto, adistance between the printed board 5 and the protrusion 27 of the cover13, that is, dimensional accuracy of the portion where the thermallyconductive material 29 is placed, can be easily ensured. Additionally,since a part of the thermally conductive thin film layers 17 a, 17 b,and 17 c is provided so as to correspond to the position where theelectronic component 3 is mounted and the remaining part thereof at theperiphery of the mount position are thermally separated from each other,there is an advantage in that the heat is hardly transferred to theperiphery through the printed board 5.

Alternatively, an area of the thermally conductive thin film layers 17a, 17 b, and 17 c on the mount face 5 a side of the printed board 5 maybe larger than that on the opposite mount face 5 b side. As a result,the heat dissipation properties are further improved. Instead ofbringing the printed board 5 and the cover 13 in direct contact witheach other, a spacer having a predetermined thickness may alternativelybe placed between the printed board 5 and the cover 13. As a result, itis possible to adjust a space therebetween.

(Embodiment 2)

Next, an electronic control unit of Embodiment 2 will be described.Descriptions similar to that of the above-described Embodiment 1 will beomitted.

a) An electronic control unit of Embodiment 2 will be described withreference to FIG. 2.

As shown in FIG. 2, also in an electronic control unit (ECU) 31, aprinted board 33 is interposed between a case 35 and a cover 37 so as tobe fixed therebetween, in a similar manner to that of theabove-described Embodiment 1. Thermally conductive thin film layers 41 aand 41 b, each having a similar shape to that obtained by projecting anelectronic component 39, are respectively formed on a mount face 33 aand an opposite mount face 33 b of the printed board 33. At the sametime, holes 43 are formed through the printed board 33 so as to connectthe thermally conductive thin film layers 41 a and 41 b on both sides toeach other.

A copper foil is formed on an inner peripheral face of each of thethrough holes 43. Each of the through holes 43 is filled with a solder45. The thermally conductive thin film layers 41 a and 41 b are formedso as to overlap a region obtained by projecting the electroniccomponent 39 onto the printed board 33 side (that is, so as to be largerthan a region obtained by the projection).

The electronic component 39 is molded along with a lead frame 47, abonding wire 49 and a radiator member (a radiator fin or a heat sink) 51through a resin 53. This molded component (hereinafter, also indicatedby the reference numeral 55) 55 is bonded to the thermally conductivethin film layer 41 a on the mount face 33 a of the printed board 33through the radiator member 51 with a solder 57.

A protrusion 59, which protrudes from a bottom part 37 a of the cover 37toward the position where the electronic component 39 is mounted, isprovided on the cover 37. The protrusion 59 is integrally formed withthe cover 37 in a solid form.

Also in this embodiment, a flexible semi-solid thermally conductivematerial 61 is placed between an end face 59 a of the protrusion 59 andthe opposite mount face 33 b of the printed board 33 (corresponding tothe position where the electronic component 39 is mounted) so as to bein contact with the end face 59 a and the opposite mount face 33 b.

b) This Embodiment 2 has a similar effect to that of the above-describedEmbodiment 1. In particular, since the through holes 43 are formed so asto connect the thermally conductive thin film layers 41 a and 41 b onthe mount face 33 a and the opposite mount face 33 b to each other, thisembodiment is effective in that the heat dissipating ability is furtherimproved. Thus, this embodiment is suitable for an electronic componenthaving a relatively large amount of heat generation.

(Embodiment 3)

Next, an electronic control unit of Embodiment 3 will be described.Descriptions that are the same as in the above-described Embodiment 2will be herein omitted.

a) An electronic control unit of Embodiment 3 will be described withreference to FIG. 3.

As shown in FIG. 3, a fundamental structure of an electronic controlunit 70 of Embodiment 3 is similar to that of the above-describedEmbodiment 2.

However, in this embodiment, a convex-shaped movement-stopping part(movement-stopping frame part) 77 for preventing a thermally conductivematerial 75 from flowing out to the periphery is provided on an end face73 a of a protrusion 73 of a cover 71. This movement-stopping part 77 isformed to have a rectangular frame-like shape so as to surround theperiphery of the end face 73 a of the protrusion 73, as shown in FIG. 4Awhich illustrates a plan view thereof. As shown in FIG. 3, themovement-stopping part 77 protrudes from the end face 73 a toward theopposite mount face 79 b side of the printed board 79. Themovement-stopping part 77 is integrally formed with the protrusion 73and thus, with the cover 71.

b) This Embodiment 3 produces a similar effect to that of theabove-described Embodiment 2. At the same time, since the frame-likemovement-stopping part 77 is formed on the end face 73 a, the thermallyconductive material 75 can be effectively prevented from flowing out.Furthermore, since the movement-stopping part 77 is integrally formedwith the protrusion 73, there is an advantage in that the formation ofthe movement-stopping part 77 is facilitated.

In the case where the thermally conductive material 75 is not highlyfluid, for example, as in the case of a sheet-like one, convex portions81 may be partially provided, for example, at the periphery of the endface 73 a of the protrusion 73 as shown in FIG. 4B. Moreover, instead ofproviding the movement-stopping part 77 on the protrusion 73 side, amovement-stopping part having a similar shape to that shown in FIG. 4Bmay be provided by, for example, soldering, on the opposite mount face79 b on the printed board 79.

(Embodiment 4)

Next, an electronic control unit of the fourth Embodiment will bedescribed. Descriptions that are the same as those of Embodiment 3 willbe herein omitted.

a) An electronic control unit of Embodiment 4 will be described based onFIG. 5.

As shown in FIG. 5, the fundamental structure of the electronic controlunit 90 of Embodiment 4 is similar to that of the above-describedEmbodiment 3. In this embodiment, in particular, a large number ofconvex portions 95 are provided on an end face 93 a of a protrusion 93of a cover 91, so that the end face 93 a in a convex-concave shape isformed. Simultaneously, a large number of convex portions 103 aresimilarly provided on a thermally conductive thin film layer 101 formedon an opposite mount face 99 b of a printed board 99 (the thermallyconductive thin film layer 101 being provided so as to correspond to theposition where a molded component 97 is mounted), so that a surface ofthe thermally conductive thin film layer 101 has a convex-concave shape.

The surfaces of the end face 93 a and the thermally conductive thin filmlayer 101 are shaped so that the convex and concave portions on the endface 93 a of the protrusion 93 correspond to those of the thermallyconductive thin film layer 101.

A thermally conductive material 105 is placed between the concave-convexshaped end face 93 a of the protrusion 93 and the concave-convex shapedthermally conductive thin film layer 101, resulting in a meanderingcross-sectional shape of the thermally conductive material 105. However,a thickness of the thermally conductive material 105 is approximatelyuniform.

The convex portions 95 of the protrusion 93 are integrally formed withthe protrusion 93 (thus with the cover 91), whereas the convex portions103 on the opposite mount face 99 b side of the printed board 99 areformed by soldering.

b) This Embodiment 4 also produces a similar effect to that of theabove-described Embodiment 3. At the same time, since the thermallyconductive material 105 is interposed between the concave-convex shapedend face 93 a of the protrusion 93 and the concave-convex shapedthermally conductive thin film layer 101 to form a large contact areatherebetween, this embodiment is effective in that even higher heatdissipation properties can be obtained than a design that is notconcave-convex shaped.

Since the convex-concave portions on the end face 93 a of the protrusion93 and the convex-concave portions on the thermally conductive thin filmlayer 101 fit each other to create a uniform distance between theconvex-concave surface of the end face 93 a of the protrusion 93 andthat of the thermally conductive thin film layer 101, the heat transferis also uniform. Therefore, such a structure is effective in that even aminimum of thermally conductive material 105 offers the maximum in heatdissipation properties. Moreover, since only a small amount of thethermally conductive material 105 is necessary, a cost reduction is alsorealized.

(Embodiment 5)

Next, an electronic control unit of Embodiment 5 will be described.Descriptions similar to those of Embodiment 3 will be herein omitted.

a) An electronic control unit of Embodiment 5 will be described withreference to FIG. 6. As shown in FIG. 6, an electronic control unit 110differs from that of the above Embodiment 3 in that a main body part 113a of a molded component 113 housing an electronic component 111 thereinis not in contact with a printed board 115 and in that the printed board115 does not have any through holes.

More specifically in this embodiment, the molded component 113 is placednot on a case 117 side but on a cover 119 side. Moreover, a radiatormember 121 is placed not on the printed board 115 side, but on the cover119 side. A thermally conductive material 125 is placed between theradiator member 121 and a protrusion 123 of the cover 119.

A frame-like movement-stopping part 127 as described above is formed onan end face 123 a of the protrusion 123 of the cover 119.

b) In this embodiment, the molded component 113 is placed in a reverseposition with respect to Embodiments 1 to 4 described above. Since themain body part 113 a of the molded component 113 is not in directcontact with the printed board 115, the heat is minimally transferred tothe printed board 115 side, thereby providing even higher heatdissipation properties.

Moreover, the movement-stopping part 127 can prevent the thermallyconductive material 125 from flowing out. Although the movement-stoppingpart 127 is provided on the protrusion 123 side in this embodiment, asimilar movement-stopping part may also be provided on the radiatormember 121 side.

(Embodiment 6)

Next, an electronic control unit of Embodiment 6 will be described.Descriptions similar to that of Embodiment 1 described above will beherein omitted.

a) An electronic control unit of Embodiment 6 will be described withreference to FIG. 7. As shown in FIG. 7, an electronic control unit 130of Embodiment 6 includes a printed board 131, a molded component 133 anda cover 135 (formed by pressing), similar to those of theabove-described Embodiment 1.

As in the above-described Embodiment 4, in this embodiment, a number ofconvex portions 139 are provided on an end face 137 a of a protrusion137 of the cover 135 so as to form the convex-concave shaped end face137 a. At the same time, a number of convex portions 143 are similarlyprovided on a thermally conductive thin film layer 141 on an oppositemount face 131 b of the printed board 131 so as to provide aconvex-concave shaped surface for the thermally conductive thin filmlayer 141.

Moreover, the convex-concave portions on the end face 137 a of theprotrusion 137 and those on the thermally conductive thin film layer 141are formed so as to correspond to each other. A thermally conductivematerial 145 is placed between the convex-concave shaped end face 137 aof the protrusion 137 and the convex-concave shaped surface of thethermally conductive thin film layer 141.

The convex portions 139 on the protrusion 137 are integrally formed withthe protrusion 137 (thus with the cover 135), whereas the convexportions 143 on the opposite mount face 131 b side of the printed board131 are formed by soldering.

b) This embodiment also produces a similar effect to that of theabove-described Embodiment 4. In addition, the convex portions 139 onthe protrusion 137 are integrally formed with the protrusion 137 (andthus with the cover 135), whereas the convex portions 143 on theopposite mount face 131 b side of the printed board 131 are formed bysoldering. Therefore, both of the convex portions 139 and 143 are formedonly with original material. More specifically, this embodiment iseffective in that the heat dissipation properties can be improvedwithout requiring any additional cost.

(Embodiment 7)

Next, an electronic control unit of Embodiment 7 will be described.Descriptions that are the same as those of Embodiment 1 described abovewill be herein omitted.

a) An electronic control unit of Embodiment 7 will be described withreference to FIG. 8. As shown in FIG. 8, an electronic control unit 150of Embodiment 7 includes a printed board 151, a molded component 153 andthe like, similar to those of the above-described Embodiment 1.

In particular, in this embodiment, no protrusion is formed on the cover155. A thermally conductive member 157 serving as a solid surface mountdevice (SMD) is placed between the cover 155 and an opposite mount face151 b of the printed board 151, whereas a thermally conductive material159 is placed between the thermally conductive member 157 and the cover155.

The thermally conductive member 157 is bonded onto a thermallyconductive thin film layer 161 formed on the opposite mount face 151 bof the printed board 151 (so as to correspond to the position where anelectronic component 161 is mounted) with a solder 163. Moreover, anumber of convex portions 165 are provided on an end face 157 a on thecover 155 side so as to form the convex-concave shaped end face 157 a.

On the other hand, a number of convex portions 167 are similarlyprovided on a surface of the cover 155 opposed to the thermallyconductive member 157 so as to form a convex-concave shaped surface ofthe cover 155. The convex portions 165 of the thermally conductivemember 157 are integrally formed with the thermally conductive member157 (or formed by soldering). The convex portions 167 on the cover 155side are also integrally formed with the cover 155.

b) This Embodiment 7 has a similar effect to that of the above-describedEmbodiment 1. Moreover, since the thermally conductive material 159 isinterposed vertically between the convex-concave shaped surfaces, heatcan be effectively transferred from the thermally conductive member 157to the cover 155 side. As a result, heating of peripheral components canbe minimized.

Furthermore, since the thermally conductive material 159 is interposedvertically between the convex-concave shaped surfaces, this embodimentis advantageous because it exhibits excellent heat dissipationproperties and the like as in the above-described Embodiment 4.

(Embodiment 8)

Next, an electronic control unit of Embodiment 8 will be described.Descriptions that are the same as those of Embodiment 5 described abovewill be herein omitted.

a) First, an electronic control unit of Embodiment 8 will be describedwith reference to FIG. 9. As shown in FIG. 9, in an electronic controlunit 170 of this embodiment, a molded component 171 is placed not on acase 173 side but on a cover 175 side, as in the above-describedEmbodiment 5.

More specifically, in this embodiment, a radiator member 177 is placednot on a printed board 179 side but on the cover 175 side. A thermallyconductive material 183 is placed between the radiator member 177 and aprotrusion 181 of the cover 175. In particular, in this embodiment, aplurality of convex portions 185 are provided on an end face 181 a ofthe protrusion 181 of the cover 175, so that the end face 181 a has aconvex-concave shape.

The convex portions 185 are integrally formed with the cover 175.

b) Similarly to the above-described Embodiment 5, a main body part 171 aof the molded component 171 is not in direct contact with the printedboard 179 in this embodiment. Therefore, the heat is minimallytransferred to the printed board 179 side, resulting in further higherheat dissipation properties. Since a number of convex portions 185 areformed on the end face 181 a of the protrusion 181 to provide a largecontact area, this structure is advantageous in its high heat radiatingefficiency. Although the convex portions 185 are provided on theprotrusion 181 side, a number of similar convex portions may be providedon the radiator member 177 side.

(Embodiment 9)

Next, an electronic control unit of Embodiment 9 will be described.Descriptions that are the same as that of Embodiment 4 described abovewill be herein omitted.

a) An electronic control unit of Embodiment 9 will be first describedwith reference to FIG. 10. As shown in FIG. 10, an electronic controlunit 190 of this embodiment includes a molded component 191, a printedboard 193, and a cover 197 (having a protrusion 195), which are similarto those of the above-described Embodiment 4.

In this embodiment, in particular, a thermally conductive thin filmlayer 201 is formed on an opposite mount face 193 b side of the printedboard 193 (so as to be opposed to the position where an electroniccomponent 199 is mounted), while a movement-stopping part 205 projectingtoward the protrusion 195 of the cover 197 is provided so as to surroundthe outer periphery of a thermally conductive material 203. Themovement-stopping part 205, which is made of a solder, is formed in arectangular frame-like shape along the outer periphery of the thermallyconductive thin film layer 201 (thus, having the same shape as that ofthe outer periphery of the protrusion 195).

b) Since the movement-stopping part 205 is formed at the periphery ofthe thermally conductive material 203 in this embodiment, the thermallyconductive material 203 can be prevented from flowing out.

More specifically, in the case where a viscous semi-fluid thermallyconductive material is used as the thermally conductive material 203, itis not necessary to thinly apply the thermally conductive material 203.Instead, for example, it is sufficient to use a rather larger amount ofthe thermally conductive material 203, compared to the volume of a spacewhere the thermally conductive material 203 is to be placed, so as tojoin the printed board 193 and the cover 197 to each other. Thus, in thecase of this combination, an excessive part of the thermally conductivematerial 203 is pushed away after the thermally conductive materialfills the area surrounded by the movement-stopping part, prior toflowing out to the exterior area. Therefore, such a combination allowsthe application of the thermally conductive material to be ensured witha simple operation.

Furthermore, even in the case where the electronic control unit 190 islongitudinally placed, the thermally conductive material 203 does notflow out because the movement-stopping part 205 prevents the thermallyconductive material 203 from moving as well as flowing out.

(Embodiment 10)

Next, an electronic control unit of Embodiment 10 will be described.Descriptions the same as that of Embodiment 7 described above will beherein omitted.

a) An electronic control unit of Embodiment 10 will be first describedwith reference to FIG. 11. As shown in FIG. 11, an electronic controlunit 210 of this embodiment includes a molded component 211, a printedboard 213, and the like, which are substantially the same as those ofthe above-described Embodiment 7. This embodiment differs fromEmbodiment 7 in that through holes 215 are provided through the printedboard 213.

In this embodiment, no protrusion is formed on a cover 216. Moreover, athermally conductive member 217 serving as a solid surface mount device(SMD) is placed between the cover 216 and an opposite mount face 213 bof the printed board 213, whereas a thermally conductive material 219 isplaced between the thermally conductive member 217 and the cover 216.The thermally conductive member 217 is bonded onto a thermallyconductive thin film layer 223 formed on the opposite mount face 213 bof the printed board 213 (so as to correspond to the position where theelectronic component 221 is mounted) through a solder 225. Moreover, amovement-stopping part 227 is provided on an end face 217 a of thethermally conductive member 217 so as to surround the periphery of thethermally conductive material 219.

The movement-stopping part 227 is a convex portion, which is formed in aframe-like shape along the periphery of the thermally conductive member217 so as to project from the thermally conductive member 217 sidetoward the cover 216 side. The movement-stopping part 227 is integrallyformed with the thermally conductive member 217.

b) The placement of the thermally conductive member 217 allows high heatradiating characteristics to be obtained in this embodiment, as in theabove-described Embodiment 7. In particular, in this embodiment, sincethe movement-stopping part 227 is provided on the thermally conductivemember 217 side, the common cover 216 can be used without changing thedesign of the cover 216 even if the placement of the thermallyconductive member 217 is freely changed (that is, the cover 216 can bestandardized). Therefore, since the same enclosure can be used forvarious products, such a structure greatly contributes to a reduction incost.

Moreover, other than this embodiment, for example, a thermallyconductive thin film layer may be provided at a location inside theprinted board, corresponding to the position where the electroniccomponent 221 is mounted, without providing any through hole 215.Moreover, the thermally conductive thin film layers on the surfaces ofthe printed board and inside the printed board may be thermallyseparated from each other.

The present invention is by no means limited to the above-describedembodiments. The present invention can be carried out in various modeswithout departing from the scope or gist of the present invention. Forexample, although the enclosure is constituted by the case and the coverin each of the above-described embodiments, a third member other thanthe case and the cover can be combined therewith. Moreover, the case andthe cover may have a similar size.

1. An electronic control unit comprising: a substrate having a mountface and an opposite mount face; an electronic component located on aside of the mount face, wherein the electronic component generates heat;and an enclosure housing the substrate therein, wherein: a solid,thermally conductive member is placed between the opposite mount faceand the enclosure so as to be in contact with a side of the oppositemount face and a side of the enclosure; a flexible, thermally conductivematerial is placed between the thermally conductive member and theenclosure to be in contact with a side of the thermally conductivemember and the side of the enclosure; the enclosure includes a case anda cover, which are integrated for housing the substrate; and thethermally conductive member is soldered to the opposite mount face. 2.The electronic control unit according to claim 1, wherein at least onesurface of the thermally conductive member and the enclosure is formedto have a convex-concave shape and the at least one surface being is incontact with the thermally conductive material.
 3. The electroniccontrol unit according to claim 2, wherein the convex-concave shape ofthe enclosure is integrally formed with the enclosure.
 4. The electroniccontrol unit according to claim 2, wherein the convex-concave shape ofthe thermally conductive member is integrally formed with the thermallyconductive member.
 5. The electronic control unit according to claim 2,wherein the convex portion and the concave portion of the enclosure arerespectively formed so as to correspond to the convex portion and theconcave portion of the thermally conductive member.
 6. The electroniccontrol unit according to claim 1, wherein the substrate is directlymounted between the case and the cover with a screw.
 7. The electroniccontrol unit according to claim 1, wherein the thermally conductivemember includes a movement-stopping part for protecting the thermallyconductive material from flowing out to a periphery of the substrate. 8.An electronic control unit according to claim 1 further comprising amovement-stopping part, which protrudes toward a side of the thermallyconductive material and prevents the thermally conductive material frommoving and which is provided on at least one surface of the oppositemount face and the thermally conductive member, the at least one surfacebeing in contact with the thermally conductive material.
 9. Theelectronic control unit according to claim 8, wherein themovement-stopping part is integrally formed with the thermallyconductive member or the enclosure.
 10. The electronic control unitaccording to claim 8, wherein the thermally conductive member issoldered onto the opposite mount face.
 11. The electronic control unitaccording to claim 8, wherein thermally conductive thin film layers,each having a higher thermal conductivity than that of a peripherythereof, are respectively provided on the mount face and the oppositemount face so as to overlap a region obtained by projecting theelectronic component thereon, and the thermally conductive thin filmlayers are connected to each other via a through hole.
 12. Theelectronic control unit according to claim 8, wherein thermallyconductive thin film layers, each having a higher thermal conductivitythan that of a periphery thereof, are respectively provided on the mountface and the opposite mount face and inside the substrate so as tooverlap a region obtained by projecting the electronic componentthereon.
 13. The electronic control unit according to claim 8, wherein,other than the thermally conductive thin film layer corresponding to theregion obtained by projecting the electronic component thereon, athermally conductive thin film layer is provided at another location ofthe substrate, and thermally conductive thin film layers are thermallyseparated from each other.
 14. An electronic control unit comprising: asubstrate having a mount face and an opposite mount face; an electroniccomponent located on a side of the mount face, wherein the electroniccomponent generates heat; and an enclosure housing the substratetherein, wherein: a solid, thermally conductive member is placed betweenthe opposite mount face and the enclosure so as to be in contact with aside of the opposite mount face and a side of the enclosure; a flexible,thermally conductive material is placed between the thermally conductivemember and the enclosure to be in contact with a side of the thermallyconductive member and the side of the enclosure; and at least onesurface of the thermally conductive member and the enclosure is formedto have a convex-concave shape and the at least one surface being is incontact with the thermally conductive material.
 15. The electroniccontrol unit according to claim 14, wherein the convex-concave shape ofthe enclosure is integrally formed with the enclosure.
 16. Theelectronic control unit according to claim 14, wherein theconvex-concave shape of the thermally conductive member is integrallyformed with the thermally conductive member.
 17. The electronic controlunit according to claim 14, wherein the convex portion and the concaveportion of the enclosure are respectively formed so as to correspond tothe convex portion and the concave portion of the thermally conductivemember.
 18. The electronic control unit according to claim 14, whereinthe enclosure includes a case and a cover, which are integrated forhousing the substrate, and the substrate is directly mounted between thecase and the cover with a screw.
 19. The electronic control unitaccording to claim 14, wherein the thermally conductive member includesa movement-stopping part for protecting the thermally conductivematerial from flowing out to a periphery of the substrate.
 20. Anelectronic control unit comprising: a substrate having a mount face andan opposite mount face; an electronic component located on a side of themount face, wherein the electronic component generates heat; anenclosure housing the substrate therein; and a movement-stopping part,which protrudes toward a side of the thermally conductive material andprevents the thermally conductive material from moving and which isprovided on at least one surface of the opposite mount face and thethermally conductive member, the at least one surface being in contactwith the thermally conductive material, wherein: a solid, thermallyconductive member is placed between the opposite mount face and theenclosure so as to be in contact with a side of the opposite mount faceand a side of the enclosure; and a flexible, thermally conductivematerial is placed between the thermally conductive member and theenclosure to be in contact with a side of the thermally conductivemember and the side of the enclosure.
 21. The electronic control unitaccording to claim 20, wherein the movement-stopping part is integrallyformed with the thermally conductive member or the enclosure.
 22. Theelectronic control unit according to claim 20, wherein the thermallyconductive member is soldered onto the opposite mount face.
 23. Theelectronic control unit according to claim 20, wherein thermallyconductive thin film layers, each having a higher thermal conductivitythan that of a periphery thereof, are respectively provided on the mountface and the opposite mount face so as to overlap a region obtained byprojecting the electronic component thereon, and the thermallyconductive thin film layers are connected to each other via a throughhole.
 24. The electronic control unit according to claim 20, whereinthermally conductive thin film layers, each having a higher thermalconductivity than that of a periphery thereof, are respectively providedon the mount face and the opposite mount face and inside the substrateso as to overlap a region obtained by projecting the electroniccomponent thereon.
 25. The electronic control unit according to claim20, wherein, other than the thermally conductive thin film layercorresponding to the region obtained by projecting the electroniccomponent thereon, a thermally conductive thin film layer is provided atanother location of the substrate, and thermally conductive thin filmlayers are thermally separated from each other.
 26. The electroniccontrol unit according to claim 20, wherein the enclosure includes acase and a cover, which are integrated for housing the substrate, andthe substrate is directly mounted between the case and the cover with ascrew.
 27. The electronic control unit according to claim 20, whereinthe thermally conductive member includes a movement-stopping part forprotecting the thermally conductive material from flowing out to aperiphery of the substrate.